patriandClaude Opus 5.5
c9fb70ad10
- background page (4th tile): built-in or any GIF in /gifs on the SD card - chosen GIF is copied into a raw 11.9 MB 'bggif' flash partition (header written last) and played memory-mapped from flash; SD only needed when choosing or when the file changed (checked at boot in the background) - own partitions.csv: 4 MB app + bggif + NVS - tools/gif_to_360.py: convert GIFs to 360x360 keeping frame timing; converted output (12-OBD-Speed/sd/) is git-ignored Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
52 lines
3.8 KiB
Markdown
52 lines
3.8 KiB
Markdown
# OBD Speed (JC3636W518)
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Vehicle speed from an ELM327 over BLE, shown as a big number + arc gauge on top of an animated GIF.
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Uses the shared board library and LVGL 9.6 (`../shared`), NimBLE-Arduino 2.5.1.
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## Use
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- **Speed page** — speed in km/h (`--` = no data: not connected, or ignition off), arc gauge 0–200 km/h,
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status pill below the number (adapter name when running, otherwise what it is doing).
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**Battery voltage** (`ATRV`, every 2 s) as a small arc in the bottom gap (11–15 V) + number; color:
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red < 11.8 V, orange < 12.2 V, green < 13.0 V (resting OK), blue ≤ 14.8 V (charging), red above (overcharge).
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- **Swipe left → adapter menu** — scans while open. OBD-like adapters (name OBD/ELM/…, or service FFF0/FFE0/18F0)
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are listed first in green. **Tap one** to select it: it is remembered (NVS) and connected immediately.
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**Forget** clears the remembered adapter, **Done** (or swipe right) returns to the speed page.
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- **Swipe left again → settings** — screen rotation 0 / 90 / 180 / 270 degrees, and **screen off without data** Off / 2 / 5 / 10 min (default 2). Both remembered in NVS.
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- **Swipe left once more → background** — `Built-in` plus every GIF in `/gifs` on the SD card (size and
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dimensions shown; not 360×360 in orange). Tap one: it is copied into the device's flash (progress shown) and
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played from there, so the SD card is not needed afterwards. At boot the device checks (in the background)
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whether the chosen file on the SD card changed (size/date) and re-copies it. **Rescan** re-reads the card.
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- **Idle** — after that time without speed data (ignition off, adapter gone) the screen goes dark, the GIF pauses and
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OBD polling stops; only `ATRV` every 30 s (answered by the adapter itself, doesn't wake the car's bus).
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Wakes on a touch (the touch is swallowed) or by itself when the voltage rises above 13.2 V (engine started).
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Not used while no adapter is chosen.
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- On power-up the remembered adapter is connected automatically; if the link drops or the adapter is not
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there (car off), it retries every 3 s. With no adapter remembered, the device starts on the menu page.
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## How it talks to the ELM327
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Service `FFF0`, notifications + commands on `FFF1` (verified with the user's "OBDII" adapter, see
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`docs/2026-10-23_ble_scanner_car_test.txt`, made with the BLE scanner tool that was removed afterwards — in git history); other adapters: first notify+write pair.
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Init: `ATZ`, `ATE0`, `ATL0`, `ATS0`, `ATH0`, `ATSP0`, `0100`; then `010D` (speed) is polled continuously.
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Serial (115200) prints status changes as `[obd] ...`.
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## Files
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| File | What |
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|---|---|
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| `src/main.cpp` | LVGL UI (tileview: speed page + menu page) |
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| `src/obd_link.cpp/.h` | BLE scan, connect/reconnect, ELM327 init and speed polling (background task on core 0) |
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| `src/font_speed_120.c` | Montserrat Medium 120 px, digits and `-`, 4 bpp (generated with `lv_font_conv`, see header) |
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| `src/bg_store.cpp/.h` | Background GIF from the SD card: list `/gifs`, copy into the `bggif` flash partition (header written last), mmap for playback, change check at boot (background task) |
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| `partitions.csv` | 4 MB app (no OTA) + 11.9 MB `bggif` raw area + NVS |
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| `data/bg.gif` | Built-in background (`ezgif-5-cb56986bc7.gif`, 360×360), linked into the firmware via `board_build.embed_files` |
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| `sd/gifs/` | (not in git) GIFs converted with `../tools/gif_to_360.py`, ready to copy to the SD card |
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## GIFs for the SD card
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Convert any GIF to 360×360 (scale to cover, center crop, frame timing kept) with
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```
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pip install pillow
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python ../tools/gif_to_360.py <gif files or folders> -o sd/gifs
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```
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and copy the files into a folder `gifs` on the SD card. Max ~11.5 MB per GIF. GIFs are played from flash at their own
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frame rate (360×360: ~10–12 ms decode per frame).
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Replace `data/bg.gif` to change the built-in background.
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